News in Context: DBS Trial Results

4/29/2010

On April 29, 2010 the journal, Lancet Neurology, published the article, “Deep brain stimulation plus best medical therapy versus best medical therapy alone for advanced Parkinson’s disease (PD SURG trial): a randomized, open-label trial.” NPF’s National Medical Director, Dr. Michael Okun, explains why this DBS trial is important and how it will help guide DBS therapy into the future.

A: The PD SURG trial results (conducted by a multicenter team of collaborative investigators from all over Britain) include a one year follow-up of Parkinson’s disease deep brain stimulation (DBS) patients. The trial was randomized, and it compared DBS to best medical therapy. The primary outcome variable was quality of life, and interestingly, patients in the best medical therapy arm had access to apomorphine pumps. Though sites were allowed to use the subthalamic nucleus target, the globus pallidus interna target, and even lesion therapy (e.g. pallidotomy), 174/178 (98%) of patients in the surgery group were implanted with subthalamic nucleus DBS.

Q: What were the results of the trial?

A: There was a five point improvement noted in quality of life scores in the surgical compared to medical group. Although compared to other studies the quality of life improvement was less robust, this may have reflected a longer study duration, or potentially even disease progression. There were unmistakable improvements in dyskinesias, and on time in the surgical group, although diaries were not utilized.

Q: Why is this study unique?

A: Though, not a perfect trial, its large size and use of a medical control group along with unique access to apomorphine made it unique among available DBS publications. The results underscored the powerful influence that DBS can have on motor fluctuations. Additionally, these SURGE investigators are planning a long term (9 year) follow-up, and this will surely enlighten the field as to disease progression, and other issues potentially important to DBS cohorts.

One unique and hidden aspect of this trial was the report of the “reasons why patients sought DBS surgery.” Severe off periods, dyskinesia and tremor were far and away the most common indications cited for DBS therapy. As DBS moves into a tailoring phase (the right target and approach for a particular symptom or symptom cluster) this type of information will be very useful to clinicians.

Q: What does this mean for Parkinson’s disease patients considering DBS?

A: It is fascinating to see that 98% of implants were placed in the subthalamic nucleus in this study, despite the option for surgeons to use a different target. Though the subthalamic target has many strengths, it also has relative weaknesses. Emerging data is now strongly suggestive that the motor outcomes in pallidum and subthalamic nucleus are actually similar, and that targets in the future should be tailored for individual patients and individual symptoms. It is important to remember that surgery is not without risk.

In conclusion, can we say the PD SURGE trial was a surge forward for the PD community? The answer is certainly yes, as the publication of more carefully controlled DBS trials will be important in guiding DBS therapy into the future.